Nanoparticles are particles having one or more dimensions between 1 and 100 nanometers (nm). Due primarily to a high percentage of their atoms being positioned at the surface providing a very large surface area for their size, nanoparticles of a given material can exhibit markedly different properties and behaviours than larger particles of the same material.
Nanocomposites are multiple-phase materials, found in nature or fabricated, where one of the phases is nanoparticles. For example, a solid nanocomposite comprises nanoparticles dispersed in a bulk solid matrix. Due to the unique physical properties of nanoparticles, a small percentage of nanoparticles can have noticeable, macro-scale effects on the bulk solid matrix. As such, fabrication of nanocomposites having nanoparticles for imparting beneficial macro-scale mechanical, electrical, optical, dielectrical, thermal, antimicrobial or other effects is of great interest.
Nanofibrils, or nanowhiskers, are nanoparticles having a crystalline rod-like structure. Chitin nanowhiskers include crystalline polysaccharides having a diameter of about 10 nm and a length of about 200 nm to about 500 nm that may be found in an abundant, biodegradable and non-toxic structural polysaccharide, material found in crustaceans such as shrimp and crab, known as chitin. Chitin nanowhiskers are desirable for nanocomposites due to their ability to impart desirable mechanical and antimicrobial effects, as well as due to their biodegradability, their abundance and their non-toxicity.
In nature, chitin contains both amorphous and crystalline chitin along with various other components such as proteins and the like. For forming nanocomposites, it is desirable to extract mostly individual chitin nanowhiskers from chitin so that the individual nanowhiskers can be dispersed throughout a bulk matrix. As such, it is desirable to process the chitin to generally extract only individual chitin nanowhiskers, without also extracting agglomerated chitin nanowhiskers that can be undesirably larger in size, amorphous chitin, and the proteins or other materials.
When forming the nanocomposites on an industrial scale using chain nanowhiskers, it can be challenging to ensure that nanoparticles are generally uniformly dispersed in the bulk solid matrix. Unless the chitin nanowhiskers are dispersed in this way, an overall body of nanocomposite material will not exhibit the desirable properties uniformly. Too low a concentration of chitin nanowhiskers will have little beneficial effect, while too high a concentration of chitin nanowhiskers can undesirably weaken the material locally. Furthermore, if the overall body of nanocomposite material is to be subdivided into pellets or other smaller units prior to provision to a downstream process, there can be a wide variation in amounts of chitin nanowhiskers across individual pellets.